1. Field of the Invention
This invention relates to golf balls, and, more particularly to a golf ball which has dimples which are so placed on the surface of the ball so as to maximize the performance of the golf ball when played under the wide variety of environmental and atmospheric conditions encountered in the game of golf.
2. Description of the Prior Art
For many years the manufacturers of golf balls have attempted to maximize the distance achieved when a golf ball is struck by a golf club and more specifically when the golf ball is struck by the number 1 wood or driving club. Many patents have been granted on inventions which improve the aerodynamic performance or distance of the golf ball. The use of multiple dimple sizes, depths and shapes and the avoidance of multiple parallel rows of dimples has substantially improved the distance achieved by golf balls.
The location of the dimples on the spherical surface of the golf ball entails dividing the spherical surface of the sphere into smaller areas and locating the dimples according to the resultant constraining pattern. The platonian figures of the octahedron, dodecahedron and icosahedron have been widely used, usually being further subdivided in smaller areas so as to minimize the distortional effect of planar to spherical conversion. In addition to the platonian figures a number of geometric prism and other geodesic shapes have been used to develop dimple constraining patterns.
Many patents have been granted on improved golf balls which employ particular patterns or spatial relationships to achieve the improved performance. U.S. Pat. No. 4,141,559 relates to the use of an icosahedron as a constraining pattern in order to eliminate multiple parallel rows of dimples and circumferential paths around the surface of the ball which are not intersected by dimples. U.S. Pat. No. 4,729,861 again deals with the use of an icosahedron as a constraining pattern but specifies the spatial relationship between dimples.
While the use of these patterns improved the distance performance of the prior art ball of Taylor's U.S. Pat. No. 878,254 it was subsequently discovered that these products would not pass the USGA rule regarding symmetrical flight of the golf ball which requires that a golf ball perform the same aerodynamically when hit on the equator and spun about an axis through the equator.
As a result of this failure of the symmetry rule many new patterns and patents resulted. The most popular development was the use of multiple parting lines or dimple free great circles on the surface of the ball. U.S. Pat. Nos. 4,147,727, 4,560,168 and 4,948,143 are examples of this art. While these patterns resulted in improving the aerodynamic symmetry of the ball, the smooth bands or circumferential paths which are not intersected by dimples resulted in higher aerodynamic drag and hence shorter distance as pointed out in U.S. Pat. No. 4,141,559.
U.S. Pat. No. 4,744,564 represented a distinct departure in the means of achieving aerodynamic symmetry. By shallowing the depths and hence reducing the volume of the dimples in the polar region of the ball, the ball could be made to fly in a symmetrical manner without having a significant impact on distance. Heretofore, all golf balls had all dimples of the same size on the ball the same depth. If the ball had multiple dimple sizes, each dimple of the same size would be the same depth over the entire surface of the sphere. Further, it was well known to those skilled in the art that increasing the dimple depth on a golf ball made it fly lower while decreasing the dimple depth raised the trajectory, so it was anticipated that shallowing the dimple depths on a portion of the ball would cause the ball to fly higher. This was not the case with the ball of U.S. Pat. No. 4,744,564 however as the trajectory in the poles horizontal mode remained relatively unchanged and the trajectory in the pole over pole orientation actually decreased to match the poles horizontal mode.
Using the new dimple patterns and conventional wisdom many new products were introduced which were improvements over the prior art. Specialized products such as low trajectory balls and high trajectory balls were introduced which performed better into the wind and with a tailwind respectively. Designs such as this allowed a player to change golf balls to suit conditions and thus improve the distance achieved on a given hole and gain an advantage on the player who did not change golf balls to suit the conditions on the hole. In order to eliminate this unfair advantage the USGA established the one ball rule which requires the player to use the same type of ball for the entire round of eighteen holes of tournament play. This has led manufacturers of golf balls to direct their research efforts toward development of a golf ball which exhibits optimum performance under the broad range of conditions under which the game of golf is played.
Before describing the current invention in detail it may be useful to list some of the considerations or empirical guidelines in understanding a golf ball design and how a golf ball can be made to fly lower or higher at the designer's discretion. These could be summed up as follows;
(A) For a golf ball of a given construction, deeper dimples will cause the ball to fly lower, and shallower dimples will cause the ball to fly higher. PA1 (B) Large, shallow dimples will cause the ball to fly higher than small, deep dimples even though the large, shallow dimples have greater volume than the smaller, deeper dimples. PA1 (C) Circumferential pathways around the surface of the ball, whether they be great circles or parallels, which are not intersected by dimples and are hence smooth, create additional drag and retard the distance of the ball. FIG. 1 is a good pictorial example of this problem. Many lines can be drawn around the ball without intersecting dimples. Some of these lines are great circles or "equators" and the other lines are concentric with these great circles and hence are parallels. PA1 (D) At high altitudes the density of the air and its kinematic viscosity is less. PA1 This is directly related to aerodynamic performance and teaches us that a golf ball which performs well at sea level may not perform well at high altitudes. PA1 Conversely a golf ball which is designed to perform well for high altitude play my not perform well at sea level. PA1 (E) Cold temperatures increase the density of the air as well as its kinematic viscosity, thus affecting the aerodynamic performance of the ball. PA1 (F) Using a variety of dimple sizes on the ball has a positive effect on distance if the depth of these dimples is optimized.
Generally speaking the aerodynamic performance of a flying object such as a golf ball is dynamic and depends on the environmental condition, and there are many other facts which could be stated in regard to golf ball development.